African locusts ready for spring

Locusts afflicting Africa could multiply into larger, more voracious swarms by early next year, warn experts, following the insects' high-profile arrival at the Red Sea.

Warnings about the locusts Schistocerca gregaria (Forskal), have been coming thick and fast since late 2003, when they began to multiply in unusual numbers in northern and western Africa. When the insects band together in flying swarms, they can strip fields of crops overnight.

“There was panic in the streets.”

Entomologist, Keith CressmanFood and Agricultural Organization, Rome

The chief concern is that the locusts will escalate into a plague, which will descend upon a swath of countries and demolish precious food crops. Despite frantic efforts to control the insects, the scale of the infestation "has gradually gotten bigger and worse," says Keith Cressman, an entomologist in the locust forecasting team at the Food and Agricultural Organization, headquartered in Rome.

In the last two months, the swarms have taken an unusual turn. Winds carried them from summer breeding grounds in Mali and Niger towards the Mediterranean coasts of Libya and Egypt, and even to the islands of Crete and Cyprus. Locusts have not moved this way, from northwest to southeast, since the 1950s.

And in the last few days, the locusts have been back in the spotlight. On 17 November, a large swarm filled the midday sky above Cairo in Egypt; days later, remnants of the same swarm hit the northern Red Sea, including the beach resort of Eilat in southern Israel.

"You can imagine how many millions of people saw that... there was some panic in the streets," says Cressman.

Slow winter

Although some fear that the Red Sea insects may breed, the thickest swarms (and those of most concern) are moving north into Morocco and Algeria, where they will probably grind to a halt during the cold, dry winter months.

After this, there are two possibilities, Cressman says. In the most optimistic scenario, the spring rains fail and deny the insects the opportunity to breed by laying their eggs in damp soil. This, along with continued efforts to crush the insects with pesticides, could bring the situation under control.

The worst case scenario is one in which ample rains spur bountiful breeding and swarms emerge in greater numbers next spring to re-invade western Africa. Cressman says, "The reality will most likely be somewhere in between."